For each executable using this framework, you must call the macro "INITIALIZE_EASYLOGGINGPP" directly after you include easylogging++ for the first time. This can only be done once! So just do it in "main.cc" files. Then, every file linked with e.g. "main.cc" just #includes easylogging++.h and can use the logging stuff as necessary.

System-level configurations are turned on by #defining constants before including easylogging for the first time. Again, this should be done in a main cc file. There are a bunch of configurations, but the ones relevant to us are ELPP_FRESH_LOG_FILE (truncate or append to the log file), and ELPP_THREAD_SAFE. Thread safety is off by default. If you're building a threaded executable, be sure to define the latter macro. The first isn't as important, but I went ahead and defined that for namenode.

Logging handles

Global: Generic level that represents all levels. Useful when setting global configuration for all levels.
Trace: Information that can be useful to back-trace certain events - mostly useful than debug logs.
Debug: Informational events most useful for developers to debug application. Only applicable if NDEBUG is not defined (for non-VC++) or _DEBUG is defined (for VC++).
Fatal: Very severe error event that will presumably lead the application to abort.
Error: Error information but will continue application to keep running.
Warning: Information representing errors in application but application will keep running.
Info: Mainly useful to represent current progress of application.
Verbose: Information that can be highly useful and vary with verbose logging level. Verbose logging is not applicable to hierarchical logging.
Unknown: Only applicable to hierarchical logging and is used to turn off logging completely.

Check out config/nn-log-conf.conf and config/dn-log-conf.conf to see how the different logger options are exercised on a per-handle basis.

Using the logger

After all of this configuration, etc., using the logger is as simple as including the header file and doing: ``` LOG(HANDLE) << "My log message"; //(no endl necessary). ``` where HANDLE is one of the ones above (uppercase, so INFO, ERROR, etc. Important note: abort() is called when you log to the FATAL handle. I don't know that we'll ever want to use this handle (unless there truly is a logged event at which we want to shut everything down)

Further Information

https://github.com/easylogging/easyloggingpp

License

The MIT License (MIT)

https://github.com/easylogging/easyloggingpp http://easylogging.muflihun.com http://muflihun.com

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.